This invention relates generally to semiconductor structures and devices and to a method for their fabrication, and more specifically to semiconductor structures and devices and to the fabrication and use of semiconductor structures, devices, and integrated circuits that include a monocrystalline material layer comprised of semiconductor material, compound semiconductor material, and/or other types of material such as metals and non-metals. More particularly, this invention relates to the use of these semiconductor structures and methods of fabrication in a microprocessor application.
For many years, attempts have been made to grow various monolithic thin films on a foreign substrate such as silicon (Si). To achieve optimal characteristics of the various monolithic layers, however, a monocrystalline film of high crystalline quality is desired. Attempts have been made, for example, to grow various monocrystalline layers on a substrate such as germanium, silicon, and various insulators. These attempts have generally been unsuccessful because lattice mismatches between the host crystal and the grown crystal have caused the resulting layer of monocrystalline material to be of low crystalline quality.
If a large area thin film of high quality monocrystalline material was available at low cost, a variety of semiconductor devices could advantageously be fabricated in or using that film at a low cost compared to the cost of fabricating such devices beginning with a bulk wafer of semiconductor material or in an epitaxial film of such material on a bulk wafer of semiconductor material. In addition, if a thin film of high quality monocrystalline material could be realized beginning with a bulk wafer such as a silicon wafer, an integrated device structure could be achieved that took advantage of the best properties of both the silicon and the high quality monocrystalline material.
An example of a semiconductor device is a transistor. Transistors can be combined and organized to form a variety of circuits, logic gates, and switches. A microprocessor is a device which arranges transistors to form a combination of logic and memory blocks which together execute programs stored in memory causing data values in memory to change and for devices attached to the microprocessor to have their state changed. There are many ways known to organize a microprocessor, depending on the technology and intended use. Microprocessors are typically formed using materials from Group IV of the periodic table, such as silicon, because of its robustness, ease of fabrication, and low cost. Heretofore, the ability of integrating a microprocessor or portions thereof in certain monocrystalline semiconductor materials or compound semiconductor materials such as group III-V or II-VI semiconductor materials like gallium arsenide (GaAs), has been unattractive due to cost, fragility problems associated with the technology, and wafer size constraints. However, the implementation of a microprocessor in a material like GaAs or other similar compound semiconductor materials would open up a host of new opportunities for improved microprocessor performance such as increased switching speed, reduced device size, and optical signal routing.
Accordingly, it would be advantageous to have a microprocessor formed in a compound semiconductor material that could overcome the problems described above.